java 在java中获取下周和上周的开始和结束日期
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Get next week and previous week staring and ending dates in java
提问by kaibuki
I want to get the starting and ending dates of a week for example
例如，我想获取一周的开始和结束日期
2012-05-06 to 2012-05-12
2012-05-13 to 2012-05-19
2012-05-06 至 2012-05-12
2012-05-13 至 2012-05-19
The code I have written is
我写的代码是
currWeekCalender.add(Calendar.WEEK_OF_YEAR, 1);
String dateStart = currWeekCalender.get(Calendar.YEAR) + "-" + addZero((currWeekCalender.get(Calendar.MONTH) + 1)) + "-" + addZero(currWeekCalender.getFirstDayOfWeek());
currWeekCalender.add(Calendar.DAY_OF_MONTH,7);
String dateEnd = currWeekCalender.get(Calendar.YEAR) + "-" + addZero((currWeekCalender.get(Calendar.MONTH) + 1)) + "-" + addZero(currWeekCalender.get(Calendar.DAY_OF_MONTH));
but the results are not correct, also I want previous weeks date.
但结果不正确，我也想要前几周的日期。
Thanks
谢谢
采纳答案by Mike Samuel
Your problem is that getFirstDayOfWeek()returns the first day of the week; e.g., Sunday in US, Monday in France. It does not return a day of the month. See javadoc.
您的问题是getFirstDayOfWeek()返回一周的第一天；例如，美国的星期天，法国的星期一。它不会返回一个月中的某一天。请参阅javadoc。
The first day in a month that is the start of the week is (in pseudo-code)
一个月中的第一天是一周的开始（在伪代码中）
((7 + (firstDayOfWeek - dayOfWeek(firstOfMonth))) % 7) + 1
You can translate that into java.util.Calendarcode if you like, but I would suggest using Joda time instead.
java.util.Calendar如果您愿意，您可以将其翻译成代码，但我建议您改用 Joda 时间。
also I want previous weeks date.
我也想要前几周的日期。
Just subtract seven days maybe using add
只需减去 7 天，也许使用 add
currCalendar.add(Calendar.DAY_OF_MONTH, -7)
This may involve underflow, but adddeals with that.
这可能涉及下溢，但要add处理它。
add(f, delta)adds delta to field f. This is equivalent to calling
set(f, get(f) + delta)with two adjustments:Add rule 1.The value of field f after the call minus the value of field f before the call is delta, modulo any overflow that has occurred in field f. Overflow occurs when a field value exceeds its range and, as a result, the next larger field is incremented or decremented and the field value is adjusted back into its range.
add(f, delta)将 delta 添加到字段 f。这相当于调用
set(f, get(f) + delta)有两个调整：添加规则 1.调用后字段 f 的值减去调用前字段 f 的值是 delta，以字段 f 中发生的任何溢出为模。当字段值超出其范围时会发生溢出，因此，下一个较大的字段会增加或减少，并且字段值会调整回其范围。
回答by ogniwo100
Hello to all coders :)
向所有编码员问好:)
I work on little app to dive some data from database. To calculate previous weeks start and end date i use this code:
我在小应用程序上工作以从数据库中挖掘一些数据。要计算前几周的开始和结束日期，我使用以下代码：
// Calendar object
Calendar cal = Calendar.getInstance();
// "move" cal to monday this week (i understand it this way)
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
// calculate monday week ago (moves cal 7 days back)
cal.add(Calendar.DATE, -7);
Date firstDateOfPreviousWeek = cal.getTime();
// calculate sunday last week (moves cal 6 days fwd)
cal.add(Calendar.DATE, 6);
Date lastDateOfPreviousWeek = cal.getTime();
Hope, that helps.
希望，这有帮助。
回答by freedev
Java 8 version
Java 8 版本
This prints previous 10 weeks
这将打印前 10 周
final ZonedDateTime input = ZonedDateTime.now();
for(int i = 1; i < 10; i++) {
final ZonedDateTime startOfLastWeek = input.minusWeeks(i).with(DayOfWeek.MONDAY);
System.out.print(startOfLastWeek.format(DateTimeFormatter.ISO_LOCAL_DATE));
final ZonedDateTime endOfLastWeek = startOfLastWeek.plusDays(6);
System.out.println(" - " + endOfLastWeek.format(DateTimeFormatter.ISO_LOCAL_DATE));
}
